Does Blender 2.8 have a working import-export plugin for After Effects?
You should not use Blender 2.8 for production until it is realeased. It is not stable yet and you may lose your work if you do. 

Other than that, the add-on does not seem to contain anything that is changed in the bpy API from the first glance(I might be wrong), so you could try to just find the add-on's file 
[Blender 2.80 install location]\2.80\scripts\addons\io_export_after_effects.py and change it with a text editor. If you changed the 27th line from version 2.79 to version 2.80, you would be telling Blender that it's fine to register it:

...
bl_info = {
    "name": "Export: Adobe After Effects (.jsx)",
    "description": "Export cameras, selected objects &amp; camera solution "
        "3D Markers to Adobe After Effects CS3 and above",
    "author": "Bartek Skorupa",
    "version": (0, 65),
    "blender": (2, 80, 0), # &lt;- here (2, 80, 0) instead of (2, 79, 0)
    "location": "File &gt; Export &gt; Adobe After Effects (.jsx)",
    "warning": "",
    "wiki_url": "http://wiki.blender.org/index.php/Extensions:2.6/Py/"
                "Scripts/Import-Export/Adobe_After_Effects",
    "category": "Import-Export",
}
...


I don't know if that is going to work or function as intended, but looking at the code it seems it could.

I would like to state it strongly that I do not recommend to do so and I do not reccommend to use Blender 2.8 for any production, because it is not finished yet and it may corrupt your saved files. It might not be a bad idea to carry on doing it as you do now, so you allways have a backup saved in 2.79.